Tutorials and documentation maintenance

...benchmarks/FluidParticleCoupling/MotionSettlingSphere.cpp

...marks/MotionSingleHeavySphere/MotionSingleHeavySphere.cpp

...ases/BidisperseFluidizedBed/BidisperseFluidizedBedDPM.cpp

apps/tutorials/basics/01_BlocksAndFields.dox

apps/tutorials/basics/02_Sweeps.dox

apps/tutorials/basics/03_GameOfLife.dox

apps/tutorials/mesa_pd/01_MESAPD.dox

apps/tutorials/pde/01_SolvingPDE.dox

apps/tutorials/pde/02_HeatEquation.dox

apps/tutorials/pde/03_HeatEquation_Extensions.cpp

apps/tutorials/pe/01_ConfinedGas.dox

apps/tutorials/pe/02_ConfinedGasExtended.dox

src/blockforest/BlockForest.h

src/blockforest/BlockNeighborhoodConstruction.cpp

src/blockforest/Initialization.cpp

src/blockforest/communication/DirectionBasedReduceScheme.h

src/blockforest/loadbalancing/DynamicCurve.h

src/communication/doc/walberlaCommunication.dox

src/core/UniqueID.h

src/core/cell/Cell.h